Transcript for Red Flags That May Have Prevented Oregon School Bombing

School bomb plot authorities say -- teenager. Had a plan bigger than column -- The weapons they say hidden underneath is bedroom floor and tonight as that school is swept so many questions from fellow students who now say. There were warning signs ABC's Lindsay Janice on this again tonight. Tonight new revelations seventeen year old grants accord may have dropped hints to classmates about the massacre police say he was planning -- his -- high school. Police say they found a stockpile of homemade explosives in the teenager's bedroom. Pipe bombs napalm bombs Molotov cocktails along with detailed plans even -- date for an attack. Now were also learning -- spoke to classmates about making bombs you just. Walked up out of nowhere and asked if we're talking about bombs. And we noticed gonna give him a funny book and -- or known and he just -- kept going on about the different materials you need to make a pipe bomb. Stone says he wasn't alarmed at the time and there was a little strange. Is also fairly strange kid. But police say someone did report strange behavior calling 911 late Thursday night saying accord was planning to blow up this school and had asked friends to film it. Investigators rushed to -- home finding an arsenal hidden under his bedroom floor. Frantic -- face charges in court tomorrow the same day his fellow students go back to class. David -- that no explosives were found in the school.

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